The present invention relates generally to structural elements used in forming structural assemblies and frameworks and deals more specifically with a constant length strut for use in constructing such an assembly or framework.
It is known that structural assemblies and frameworks change their geometric shape due to the effects of thermal expansion and contraction and changes in mechanical loading on structural elements or struts used for attaching and interconnecting the various structural components of such structural assemblies. Although such changes are generally very small, they may have a significant affect on the accuracy of precision equipment and apparatus, such as, for example, optical measuring systems and the like supported by the structural assembly. It is desirable therefore, to provide a strut that maintains a constant length between attachment points by actively controlling deflections in the strut due to thermal expansion and contraction and due to changes in tensile and compressive loading so that the geometric shape of an assembly constructed with the struts is precisely controlled.
It is an object therefore, of the present invention to provide a strut having a constant length between attachment points.
It is another object of the present invention to provide a constant length strut having active compensation for deflections due to thermal expansion and contraction and changes in tensile and compressive loading.
It is a further object of the present invention to provide a strut that operates as an element of a closed loop servocontrol system to maintain a desired constant length between attachment points.
Other objects and advantages of the invention will be readily apparent from the following description and claims taken in conjunction with the accompanying drawings.